According to the recent development of micro-chemical technology, on-chip chemical reactions are frequently used in complex forming reactions, organic synthesis, solvent extraction, cell culture, chemical reaction control, or the like. In particular, a microchip plate called a biochip is used in a DNA test or the like.
As a matter of fact, a cycloolefin polymer (COP), a cycloolefin copolymer (COC), or the like has excellent transparency and low fluorescence and also allows a reduction in thickness, so that it is suitable for a substrate of a microchip plate.
However, in these low-fluorescent plastic materials, there is a problem that since a surface is inactive, for example, two substrates formed of the COP cannot be appropriately bonded to each other by an adhesive agent. Or, it is necessary to perform pretreatment such as ultrasonic fusion bonding, ultraviolet irradiation, matt treatment, corona treatment, or plasma treatment with respect to a surface of the substrate formed of the cycloolefin polymer (COP) or the cycloolefin copolymer (COC) before the substrates are bonded to each other by the adhesive agent.
Also, in an organic solvent disclosed in the invention described in the following Patent Citation 1, since substrates are melted and bonded to each other, there is a problem that cracks are generated in the substrate or a bonded surface, or flow paths easily collapse. Also, in a case where an organic solvent is used, a problem easily occurs in which the inside of the flow path is blocked by the organic solvent. Further, in most adhesive agents, there is also a problem that fluorescence is high.    [Patent Citation 1]: Japanese Unexamined Patent Application Publication No. 2005-80569